One other thing to consider, when you apply for a job, a boss is not allowed to ask about ones religion(unless you are a christian). And, being that there is no picture there, and surely there are other people with the same name as you, it would be as stretch for an employer to jump to the conclusion that such and such forum poster is the same as the person who works for them. As long as you do not provide your geographical location, a full name does not sound that bad. And, if you work at such a public place of employment, how likely are you to be talking about cathinfo subjects, to where your coworkers would know by the subject matter that such and such member is the person who works with you? For those who have unusual names with unusual spellings, you are not in the advantage. But, for those whose name is john smith, you have nothing to worry about. I feel pretty confident in saying I would provide my full name.
Seanjohnson, thanks for that bishop williamson link. He did a great job of answering. "Either be a man and do not speak on grave subjects in public, or be a man and when you speak about grave matters in public, stand by it fully with your full name, and especially on the internet."